bisect: avoid copying ancestor list for non-merge commits
During a bisection, hg needs to compute a list of all ancestors for every
candidate commit. This is accomplished via a bottom-up traversal of the set of
candidates, during which each revision's ancestor list is populated using the
ancestor list of its parent(s). Previously, this involved copying the entire
list, which could be very long in if the bisection range was large.
To help improve this, we can observe that each candidate commit is visited
exactly once, at which point its ancestor list is copied into its children's
lists and then dropped. In the case of non-merge commits, a commit's ancestor
list consists exactly of its parent's list plus itself. This means that we can
trivially reuse the parent's existing list for one of its non-merge children,
which avoids copying entirely if that commit is the parent's only child. This
makes bisections over linear ranges of commits much faster.
During some informal testing in the large publicly-available `mozilla-central`
repository, this noticeably sped up bisections over large ranges of history:
Setup:
$ cd mozilla-central
$ hg bisect --reset
$ hg bisect --good 0
$ hg log -r tip -T '{rev}\n'
628417
Test:
$ time hg bisect --bad tip --noupdate
Before:
real 3m35.927s
user 3m35.553s
sys 0m0.319s
After:
real 1m41.142s
user 1m40.810s
sys 0m0.285s
# closehead.py - Close arbitrary heads without checking them out first
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
'''close arbitrary heads without checking them out first'''
from mercurial.i18n import _
from mercurial import (
bookmarks,
cmdutil,
context,
error,
logcmdutil,
pycompat,
registrar,
)
cmdtable = {}
command = registrar.command(cmdtable)
# Note for extension authors: ONLY specify testedwith = 'ships-with-hg-core' for
# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
# be specifying the version(s) of Mercurial they are tested with, or
# leave the attribute unspecified.
testedwith = b'ships-with-hg-core'
commitopts = cmdutil.commitopts
commitopts2 = cmdutil.commitopts2
commitopts3 = [(b'r', b'rev', [], _(b'revision to check'), _(b'REV'))]
@command(
b'close-head|close-heads',
commitopts + commitopts2 + commitopts3,
_(b'[OPTION]... [REV]...'),
helpcategory=command.CATEGORY_CHANGE_MANAGEMENT,
inferrepo=True,
)
def close_branch(ui, repo, *revs, **opts):
"""close the given head revisions
This is equivalent to checking out each revision in a clean tree and running
``hg commit --close-branch``, except that it doesn't change the working
directory.
The commit message must be specified with -l or -m.
"""
def docommit(rev):
cctx = context.memctx(
repo,
parents=[rev, None],
text=message,
files=[],
filectxfn=None,
user=opts.get(b'user'),
date=opts.get(b'date'),
extra=extra,
)
tr = repo.transaction(b'commit')
ret = repo.commitctx(cctx, True)
bookmarks.update(repo, [rev, None], ret)
cctx.markcommitted(ret)
tr.close()
opts = pycompat.byteskwargs(opts)
revs += tuple(opts.get(b'rev', []))
revs = logcmdutil.revrange(repo, revs)
if not revs:
raise error.Abort(_(b'no revisions specified'))
heads = []
for branch in repo.branchmap():
heads.extend(repo.branchheads(branch))
heads = {repo[h].rev() for h in heads}
for rev in revs:
if rev not in heads:
raise error.Abort(_(b'revision is not an open head: %d') % rev)
message = cmdutil.logmessage(ui, opts)
if not message:
raise error.Abort(_(b"no commit message specified with -l or -m"))
extra = {b'close': b'1'}
with repo.wlock(), repo.lock():
for rev in revs:
r = repo[rev]
branch = r.branch()
extra[b'branch'] = branch
docommit(r)
return 0